Thirdly,
a range of different minimum grain sizes \(a_{\rm min}\)  is used in the literature:
\(a_{\rm min}=0.1\) –1 \(\) m (e.g. [1]}, [2]}, [3]}, [4]}; see brief review in [5]}); \(a_{\rm min}=1~\) m in [6]} but with some pile-up near \(a_{\rm min}\)  in the resulting distribution;
[7]} used a smaller value: \(a_{\rm min}=5~\) nmNot \(a_{\rm min}=5~\) m as their Appendix A states (M. Flock 2020, priv. comm.).
That their opacity curve has features at \(\lambda \ll 5\)  \(\) m suggests this, since at
\(\lambda \ll 2\pi a_{\rm min}\)  the geometric, \(\lambda \) -independent limit for the cross-section per particle \(\sigma =2\pi a^2\)  must hold (e.g. [8]})..
